Controller for fluid pressure operated devices providing high pressure to an auxiliary device

ABSTRACT

A controller for fluid pressure operated devices such as power steering systems is provided. The controller is of the type having an inlet for receiving a system fluid flow, an outlet, a pair of control fluid ports for connection to a primary fluid pressure operated device and an auxiliary fluid port for connection to an auxiliary fluid pressure operated device or system. The controller includes a valve means having a primary valve member and a follow-up valve member, the valve members defining a neutral position relative to each other. A fluid meter includes a movable member coupled to the follow-up valve member. The primary and follow-up valve members cooperate with the housing to define a first flow path including the inlet, one of the control fluid ports, the fluid meter, the other of the control fluid ports, and the outlet when the valve members are relatively displaced from the neutral position. The primary and follow-up valve members cooperate with the housing to further define a second flow path communicating between the inlet and the auxiliary fluid port when the valve members are in the neutral position. Both the first and second flow paths are capable of receiving substantially all of the system fluid flow, but with the primary fluid pressure device having priority to receive the full system fluid flow when it is needed, such as to control a power steering cylinder.

This is a continuation of application Ser. No. 507,041, filed Sept. 18,1974, now U.S. Pat. No. 3,960,234.

BACKGROUND OF THE DISCLOSURE

The present invention relates to a controller for fluid pressureoperated devices and, more particularly, to a controller capable ofproviding full system fluid flow to an auxiliary device when the primarydevice does not require the full flow.

Although the present invention is equally adaptable to any controllerfor fluid pressure operated devices wherein the controller utilizes avalve spool arrangement, it is especially advantageous when used incontrollers for power steering systems of the type employed inoff-the-road vehicles, and will be described in connection therewith.More specifically, although the invention will be described inconnection with rotatable spool-sleeve valve arrangements, it will beappreciated that the invention may also be utilized with spool valveswhich operate in response to axial movement.

A controller for a power steering system of the type to which thepresent invention pertains is described in U.S. Reissue Pat. No. 25,126,assigned to the assignee of the present invention. Controllers of thetype disclosed in the cited reissue patent have become well known in theart and generally comprise a housing having an inlet and an outlet and apair of control fluid ports, feeding a power steering cylinder. Thevehicle steering wheel is directly connected to the controller and whenin the neutral (no input torque) condition, fluid may pass from theinlet through the valve to the outlet (open center system).

When the steering wheel is rotated in one direction from the neutralposition, the valve is displaced and fluid flows from the inlet throughthe valve, to the meter, then to one of the control fluid ports to movethe power steering cylinder. When the steering wheel is rotated in theopposite direction, the valve rotates in the opposite direction andfluid flows from the inlet port through the valve, then through thefluid meter in the opposite direction, then to the other of the controlfluid ports to move the power steering cylinder in the oppositedirection.

Conventionally, controllers of the type described have utilized rotaryspool-sleeve valves to direct the flow of fluid from the inlet port inaccordance with the rotational position of the steering wheel. Ingeneral, rotary spool-sleeve valves comprise a primary valve member(spool) connected directly to the steering wheel and a follow-up valvemember (sleeve) surrounding the spool. Axially adjacent the spool andsleeve is a fluid meter, generally a gerotor having an externallytoothed member coupled to orbit within an internally toothed member heldin fixed position relative to the valve housing. The externally toothedmember is splined to a drive shaft, at the opposite end of which thedrive shaft is coupled to the sleeve, such as by a pin passingtherethrough. When the spool is rotated, fluid is permitted to flow tothe meter, causing the externally toothed member to orbit, thusimparting follow-up movement to the sleeve by means of the drive shaft.Generally, the sleeve has a plurality of orifices extending radiallytherethrough and the spool has a plurality of axially extending grooveson its outer surface to provide communication between certain of theorifices in the sleeve.

Power steering systems for off-the-road vehicles and the controllersused therein require expensive, complicated hydraulic pumping aparatusto provide the full system fluid flow capability required to actuate thepower steering cylinder. Such off-the-road vehicles frequently utilizeother hydraulically operated devices which also require approximatelythe full system fluid flow for their operation. Therefore, it has longbeen an objective of those working in the hydraulic power steering artto provide a system in which the full system fluid flow would beavailable to such an auxiliary device when not required by the steeringsystem. Conventionally, the attempts at providing such a system haveinvolved the use of a "load sensing" arrangement in which either apressure sensing or flow sensing device has been included within thecontroller to sense the demand or lack of same for full flow by thesteering system. This sensing device would, in turn, actuate a valve todivert or redirect the flow in response to a determination that the flowwas not required by the steering system and was available for theauxiliary device. Other conventional systems apply a flow control valvewith priority flow maintained by pressure compensation to supply a fixedflow rate to the primary (steering) circuit, with the excess (bypass)flow directed to a secondary circuit, thus requiring a larger pump tosupply both circuits. With certain modifications, the prior art "highpressure carryover" or "power beyond" power steering systems havegenerally conformed to the above descriptions, thus requiring some sortof sensing device built into the controller or in fluid communicationtherewith, as well as additional valving and fluid flow conduitsassociated with the controller. Thus, the controllers for such highpressure carryover systems have been substantially more complicated andexpensive than the basic controller and, in some instances, have hadcertain operational disadvantages, such as a transition from steeringoperation to auxiliary operation which is not smooth enough and/or tooslow.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to provide a powersteering system and controller for use therein having the capability offull system fluid flow to an auxiliary device, but with full priority tothe primary device (the steering system).

It is more specific object of the present invention to provide a powersteering system and controller having the capability of full systemfluid flow to either the auxiliary (high pressure carryover) circuit orprimary device, directly in response to the rotational position of thesteering wheel and controller valve means, without the need foradditional control devices, valving, or hydraulic circuitry.

It is even more specific object of the present invention to provide acontroller in which the above stated objects are achieved, and whereinthe controller valve means is utilized to direct the system fluid flowcoming from the inlet to either the auxiliary circuit or the primarydevice in response to the relative rotational positions of the valvespool and valve sleeve.

These and other objects of the present invention, which will becomeapparent within the following detailed description, are accomplished bythe provision of a controller including a housing having an inlet forreceiving the full system fluid flow, an outlet, a pair of control fluidports for connection to a primary fluid pressure operated device and anauxiliary fluid port for connection to an auxiliary circuit. Thecontroller has a valve means including a primary, rotatable valve memberand a cooperating, relatively rotatable follow-up valve member, thevalve members defining a neutral position relative to each other. Afluid meter includes a movable member coupled to the follow-up valvemember, to impart follow-up movement thereto. The primary and follow-upvalve members cooperate with the housing to define a first flow pathcommunicating from the inlet to one of the control fluid ports throughthe fluid meter and from the other of the control fluid ports to anoutlet when the valve members are relatively displaced from the neutralposition. The primary and follow-up valve members cooperate with thehousing to further define a second flow path communicating between theinlet and the auxiliary fluid port when the valve members are in theneutral position, both the first and second flow paths being capable ofreceiving substantially all of the system fluid flow.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagrammatic view of a vehicle power steering system andcontroller to which the present invention may be applied.

FIG. 2 is an enlarged view, in axial cross section, of the controllershown diagrammatically in FIG. 1.

FIG. 3 is a fragmentary, overlaying view of the valve members of thepresent invention in their neutral position.

FIG. 4 is a semi-schematic cross section taken on lines 4--4 of FIG. 3.

FIG. 5 is a side elevation of the valve spool used in the controller.

FIG. 6 is a side elevation of the valve sleeve used in the controller.

DESCRIPTION OF THE PREFERRED EMBODIMENT Steering System

Referring now to the drawings which are for the purpose of illustratinga preferred embodiment of the invention, and not for limiting the same,FIG. 1 illustrates diagrammatically a vehicle power steering system ofthe type which has become well known in the art and comprises, ingeneral, a steering wheel 11 operably connected to a controller 13 and,more specifically, to the valve means 15. The controller 13 is providedwith an inlet port 17 through which the controller 13 receives the fullsystem fluid flow from a source, such as a pump 19, which is connectedto a reservoir or tank 21 by a conduit 23. The controller 13 is alsoprovided with an outlet port 25 connected to the reservoir 21 by aconduit 27. Associated with the controller is a fluid meter 29 operablyconnected to the valve means 15 to meter or measure fluid flow inresponse to rotational movement of the steering wheel 11 and valve means15. The controller includes a left turn port 31 and a right turn port33, the left turn port 31 being fed by a flow path 35 and the right turnport 33 being fed by a flow path 37, the diagram of FIG. 1 illustratingthe system in a right turn condition, and the flow path 37 being shownconnected to the fluid meter 29. A power steering cylinder 39 isoperated by the controller 13 by means of a conduit 41 connected to theleft turn port 31, and a conduit 43 connected to the right turn port 33.The controller 13 includes an auxiliary fluid port 45, from which fluidis communicated to an auxiliary control device 47 by means of a conduit49. The auxiliary device 47 is also connected to the reservoir 21 by aconduit 51. For purposes of illustration, the power steering system ofFIG. 1 is shown in a right turn condition. It is a feature of thepresent invention that the discharge from outlet port 25 through conduit27 is kept separate from the auxiliary fluid flow from port 45 to thedevice or system 49, as opposed to, for example, using the return flow(or neutral flow) to feed the auxiliary device, in which case theauxiliary device did not have available the full system pressuredifferential.

Controller

FIG. 2 is an axial cross section of the controller 13 taken on a planesuch that none of the ports 17, 25, 35 or 37 is visible, but only theauxiliary fluid port 45. The controller 13 includes a housing 53, aplate 55, the fluid meter 29 and an end plate 57. These sections arefastened in tight engagement by a plurality of bolts 59 passing intotapped holes (not shown) in the housing 53.

The fluid meter 29 includes an internally toothed member 61 held in afixed relationship with respect to the plate 55 and end plate 57 by thebolts 59. Eccentrically disposed within the internally toothed member 61is an externally toothed member 63 having a splined central opening 65.The controller housing 53 defines a substantially cylindrical, axiallyextending opening 67 within which is rotatably disposed the valve means15. At the forward end of housing 53 in a recess 71 against which isseated an end cap 73, retained in place by a retaining ring 75.

The valve means 15 comprises a primary, rotatable valve member (spool)77, and a cooperating, relatively rotatable follow-up valve member(sleeve) 79. The spool 77 terminates at its forward end in an internalspline portion 80 for connection to an externally splined shaft (notshown) attached to steering wheel 11. The sleeve 79 is coupled to thespool 77 by means of a drive shaft 81 having, at its rearward end, acrowned splined head 83 in engagement with the splined central opening65 of the externally toothed member 63, with the drive shaft 81 beingrestrained from axial movement, in part, by a spacer 84 between splinedhead 83 and end plate 57. At the opposite end of the drive shaft 81 is abifurcated end portion 85 through which passes a transverse drive pin87. The transverse drive pin 87 passes through an opening in the spool77 and engages the sleeve 79 in a manner well known in the art, andwhich forms no part of the present invention. Disposed approximately atright angles to the pin 87 is a plurality of leaf springs 88 urgingspool 77 and sleeve 79 toward the neutral position relative to eachother. Certain other details of the construction and operation of suchcontrollers which also form no part of the present invention may bebetter understood by reference to the previously cited U.S. Reissue Pat.No. 25,126, assigned to the assignee of the present invention.

FIGS. 5 and 6 are side elevations of the valve spool and valve sleeve,respectively, on approximately the same scale as FIG. 2. In both FIGS. 5and 6, there is shown a reference plane RP oriented perpendicular to theaxes of rotation of spool 77 and sleeve 79, the plane RP being includedto facilitate an understanding of the present invention.

The valve sleeve 79 includes a pair of diametrically opposed pin holes89 (only one of which is shown in FIG. 6), adapted to engage thetransverse drive pin 87. Similarly, the valve spool 77 includes a pairof diametrically opposed pin slots 91 (only one of which is shown inFIG. 5), to permit the drive pin 87 to pass therethrough withoutengaging the spool 77, except at maximum deflection.

In connection with the subsequent description of the spool and sleeve inFIGS. 5 and 6, as well as the operational description of FIGS. 3 and 4,it should be noted that many of the apertures, orifices, passages, etc.are arranged in a mirror image with respect with the reference plane RP.Thus, such elements will be described by a reference numeral followed byeither an R or L to indicate that the element is located on the rightside or the left side, respectively, of the central reference plane RP.On the other hand, certain of the elements do not have a correspondingelement oppositely disposed about the reference plane RP and will bereferred to by use by a reference numeral alone.

Formed in the outer surface of the valve sleeve 79 is a centrallydisposed circumferential groove 93 into which a plurality of orifices 95open. Oppositely disposed about the plane RP are circumferential grooves97L and 97R which communicate, respectively, with pluralities ofpressure ports 99L and 99R. Disposed further from the reference plane RPare pluralities of meter ports 101L and 101R. Finally, valve sleeve 79includes pluralities of operating ports 103L and 103R. It should benoted that in the subject embodiment, for each of the pluralities ofports, the circumferential spacing from one port to the next issubstantially the same, and furthermore, although not all of the portsof each type are shown, there are six of each in the subject embodiment,although the number may vary.

The valve spool 77 has formed within its outer surface a pair ofcircumferential meter grooves 105L and 105R equally and oppositelydisposed about reference plane RP. It should be noted that when thevalve sleeve 79 is disposed about the valve spool member 77, the members77 and 79 will be in the same axial relationship as is shown in FIGS. 5and 6, with reference planes RP coincidental. Thus, the meter grooves105L and 105R are axially aligned with, and in fluid communication withmeter ports 101L and 101R, respectively. Extending axially inwardly(toward reference plane RP) from the meter grooves 105L and 105R arepluralities of circumferentially spaced apart passages 107L and 107R,wich are adapted to communicate with the pressure ports 99L and 99R whenthe spool 77 and sleeve 79 are in a certain relative rotationalposition. Extending axially outwardly from the meter grooves 105L and105R are pluralities of operating passages 109L and 109R, each of which,in the subject embodiment, is axially aligned with one of the passages107L or 107R. The operating passages 109L and 109R are adapted tocommunicate with the operating ports 103L and 103R, respectively, inresponse to a certain rotational relationship between the spool 77 andsleeve 79. As was noted in connection with sleeve 79, the individualpassages comprising each of the above-described pluralities of passagespreferably have uniform circumferential spacing therebetween, thecircumferential spacing between the passages preferably being the sameas that between the ports of the valve sleeve 79. Axially disposedbetween the meter grooves 105L and 105R and circumferentially disposedbetween adjacent passages 107L and 107R are a plurality of pairs ofpassages 111 and 113, the passage 11 being disposed to communicatebetween pressure port 99L and auxiliary port 95, while the passage 113is adapted to communicate between the pressure port 99R and theauxiliary port 95 when the spool 77 sleeve 79 are in the neutralposition with respect to each other, as will be explained in greaterdetail in connection with FIGS. 3 and 4.

In addition to the above-described passages formed in the outer surfaceof valve spool member 77, there is a plurality of tank ports 115L,circumferentially disposed between operating passages 109L and,oppositely disposed therefrom about reference plane RP, a plurality oftank ports 115R, circumferentially disposed between operating passages109R. Each of the tank ports 115L and 115R is disposed to be alignedwith, and in fluid communication with one of the operating ports 103Land 103R, respectively, in response to a certain relative position ofthe spool 77 and sleeve 79.

FIG. 3 is a fragmentary, overlaying view of both the valve spool 77 andvalve sleeve 79, showing about 180° of each, with the members 77 and 79being aligned in the neutral position as when the steering wheel is notbeing rotated. The solid lines indicate ports defined by the valvesleeve 79, whereas the dashed lines indicate ports and passages formedin the valve spool 77 and hidden from view by the valve sleeve 79. Inthe semi-schematic cross section shown in FIG. 4, a portion of thehousing 53 is included, making it possible to illustrate schematicallycertain passages communicating between the valve means 15 and variouscontroller ports, such as the inlet port 17, cylinder ports 31 and 33,etc. Among the passages defined by the housing 53 is an auxiliarypassage 117, a pair of sources passages 119L and 119R, oppositelydisposed meter passages 121L and 121R, and operating passages 123L and123R. It should be noted in connection with FIG. 3 that, for purposes ofclarity, circumferential grooves 93, 97L and 97R formed in the valvesleeve 79 are not shown. It will be understood, however, that because ofgrooves 97L and 97R, pressure ports 99L and 99R are always in fluidcommunication with passages 119L and 119R, respectively, regardless ofthe relative rotational position of valve spool 77 and sleeve 79.

The valve spool 77 and sleeve 79 disclosed herein may be considered ashaving, in general, three relative rotational orientations correspondingto the neutral (non-displaced) condition of the controller representedby FIGS. 3 and 4, and the left turn and right turn conditions. The leftturn and right turn conditions in and of themselves form no part of thepresent invention, but are illustrated and explained in greater detailin U.S. application Ser. No. 679,607, filed Apr. 26, 1976, which is acontinuation of Ser. No. 507,015, filed Sept. 18, 1974 now abandoned, byO. Johnson, entitled "Controller for Fluid Pressure Operated Devices",and assigned to the assignee of the present invention.

It may be appreciated that when fluid is flowing from source passages119L and 119R through ports 99L and 99R and into passages 111 and 113,it is desirable that the flow be "balanced" so that the net tangentialforce acting on the valve spool 77 is zero. This is accomplished partlyby communicating this auxiliary fluid flow into the passages 111 and 113in opposite tangential directions, and having the pairs of passagesuniformly spaced apart circumferentially around the valve spool.

Although the invention is being illustrated and described with referenceto a power steering system having a particular flow order (i.e.: inletport - fluid meter - cylinder - outlet port), it will be understood bythose skilled in the art that the system could utilize a different floworder, including, but not limited to: inlet port - cylinder - fluidmeter - outlet port. Thus, any reference hereinafter to the primary flowpath (such as is used for steering) is intended to include either of theflow orders mentioned as well as combinations thereof.

Operation

In the neutral (non-rotating or non-displaced) position of the valvemeans, fluid entering the controller 13 at inlet port 17 flows throughpassages 119L and 119R, as illustrated in FIGS. 3 and 4, enteringcircumferential grooves 97L and 97R, from where it enters pressure ports99L and 99R. As is best seen in FIG. 3, when the valve spool 77 andsleeve 79 are in the neutral position with respect to each other, eachof the pressure ports 99L is in communication with one of the passages111, and each of the pressure ports 99R is in communication with one ofthe passages 113, thus permitting the entire system fluid flow to becommunicated to the passages 111 and 113. In the subject embodiment,when the valve means is in the neutral position, substantially all ofthe system fluid flow coming from the inlet port 117 through thepassages 119L and 119R is communicated to passages 111 and 113. As mayalso be seen in FIG. 3, each of the orifices 95 defined by valve sleeve79 are disposed to be in communication with both of the passages 111 and113 when the valve means is in the neutral position. As is seen in FIG.6, fluid passing through the orifices 95 enters circumferential groove93 to provide continuous communication between the orifices 95 and thepassage 117 (shown schematically in FIG. 4, but not in FIG. 1). Thus,regardless of the orientation of the valve means 15 within thecontroller housing 53, the entire system fluid flow is directed by thevalve means through the passage 117, into the auxiliary port 45, fromwhich it is fed to an auxiliary fluid device 47 (seeFIG. 1), when thecontroller is in the neutral position and does not require the fullsystem fluid flow for operation of the steering cylinder 39.

It will be appreciated by reference to FIG. 3 that as the spool andsleeve begin to move relative to each other in either direction, theflow area permitting communication between pressure port 99L and orifice95 and the flow area permitting communication between pressure port 99Rand orifice 95 is progressively decreased. In the subject embodiment,after a small amount of relative rotational deflection, fluidcommunication between the inlet port 17 and the orifices 95 is preventedand the pressure ports 99L (or 99R) are in communication with thepassages 107L (or 107R) to initiate a right turn (or a left turn), as isdescribed in the above-mentioned application.

Although the present invention has been described in connection with avehicle power steering system, it will be apparent that it may beapplied to any controller of this type for use in a system where it isdesired to have the full system fluid flow available upon demand tooperate a primary device, while making the full system fluid flowavailable to a secondary or auxiliary device wherever the primary deviceis not being operated, the primary device having complete priority overthe secondary device. Thus, it is apparent that the present inventionachieves the above objective, and furthermore does so without the needof additional sensing devices or valving.

While the invention has been described with reference to a preferredembodiment, neither the illustrated embodiment nor the terminologyemployed in describing it is intended to be limiting; rather, it isintended to be limited only by the scope of the appended claims.

I claim:
 1. A controller including a housing having an inlet forreceiving a system fluid flow and an outlet, a pair of control fluidports adapted for connection to a primary fluid pressure operated deviceand an auxiliary fluid port adapted for connection to an auxiliary fluidpressure operated device, said controller comprising:a. valve meansrotatably disposed within said housing and defining a neutral position,an operating position, and a central plane oriented generallyperpendicular to the axis of rotation of said valve means; b. a fluidmeter associated with said housing and including a movable memberoperable to measure the volume of fluid passing through said fluidmeter; c. said valve means cooperating with said housing to define firstand second supply passages in continuous open communication with saidinlet and a first flow path including said inlet, said first and secondsupply passages, said fluid meter, one of said control fluid ports, theother of said control fluid ports, and said outlet when said valve meansis in said operating position; d. said valve means cooperating with saidhousing to define a second flow path communicating between said inletand said auxiliary fluid port when said valve means is in said neutralposition, said valve means defining first and second auxiliary passagescommunicating between said auxiliary fluid port and said first andsecond supply passages, respectively, when said valve means is in saidneutral position, said first and second supply passages and said firstand second auxiliary passages being oppositely and approximately equallydisposed about said central plane; and e. said second flow path beingcapable of communicating substantially all of said system fluid flow andsaid system fluid flow being progressively redirected from said secondflow path to said first flow path as said valve means shifts from saidneutral position toward said operating position.
 2. A controller asdefined in claim 1 wherein said valve means comprises a primary,rotatable valve member and a cooperating, relatively rotatable follow-upvalve member, said valve members defining said neutral position relativeto each other.